1. Field of the Invention
This invention relates generally to piping hangers for wells and specifically to seals for piping hangers.
2. Brief Description of the Background Art
U.S. Pat. Nos. 4,109,942 and 4,056,272, both issued to Morrill, disclose tubing hangers with seal arrangements designed to contain downhole well pressures. These patents disclose metal-to-metal seals with a frustoconical metal gasket between the tubing hanger and the wellhead and an "x" cross sectional resilient metal gasket between the hanger and the christmas tree.
While the design illustrated in these patents has many advantages, due to tolerance problems arising in part from the frustoconical arrangement of the sealing surfaces, a less than ideal seal is achieved. Moreover, the arrangement illustrated requires a relatively large number of seal members.